//#pragma GCC target ("avx2")
//#pragma GCC optimize ("Ofast")
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define F first
#define S second
#define pb push_back
const int N = 1e3+100, NN=26, mod=1e9+7;
//int gcd(int a, int b) { if (b == 0) return a; else return gcd(b, a % b); }
//int lcm(int a, int b) { return a / gcd(a, b) * b; }
//int binpow(int a,int b){if(!b)return 1; if(b&1)return a*binpow(a,b-1)%mod; int x=binpow(a,b/2); return x*x%mod;}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n, m, k;
cin >> n >> m >> k;
if(m <= 15){
bool b3 = 0;
int a[n], b[m], sum = 0, ans = 1e18;
for(int i = 0 ; i < n ; i++){
cin >> a[i];
if(a[i] < k) b3 = 1;
sum += a[i];
}
bool b2=0;
for(int i = 0 ; i < m ; i++) cin >> b[i];
if(m < k || b3 == 1){
cout << "Impossible";
return 0;
}
sort(b, b+m);
for(int mask = 0 ; mask < (1<<m) ; mask++){
vector < int > v;
for(int i = 0 ; i < m ; i++){
if((mask>>i) & 1) v.pb(b[i]);
}
if(v.size() < k) continue;
for(int i = 1; i <= n; i++){
int g=v.size()-1, kk=k;
while(kk--){
v[g]--;
g--;
}
sort(v.begin(), v.end());
}
int sum2=0;
for(auto to : v) sum2+=to;
if(sum2>=sum-(n*k) && v[0]>=0){
b2=1;
ans=min(ans, sum2-(sum-(n*k)));
}
}
if(b2==1) cout << ans;
else cout << "Impossible";
return 0;
}
int a[n + 1], b[m + 1], cnt=0, cnt2=0;
for(int i = 1 ; i <= n ; i++){
cin >> a[i];
cnt2+=a[i];
}
for(int i = 1 ; i <= m ; i++){
cin >> b[i];
cnt+=b[i];
}
map < int , int > mp;
for(int i=1;i<=m;i++){
int sum=b[i];
mp[sum]=1;
for(int j=i+1;j<=m;j++){
sum+=b[j];
mp[sum]=1;
}
}
int ans=1e18;
for(int i=cnt2;i<=cnt;i++){
if(mp[i]==1){
ans=i;
break;
}
}
if(ans==1e18) cout << "Impossible";
else cout << ans-cnt2;
}
